1. Field of the Invention
The present invention is directed to a method and apparatus for authenticating legitimate articles and for detecting counterfeit articles. More particularly, the present application is directed to a method and apparatus for authenticating a legitimate article and detecting a counterfeit article in which the legitimate article has a label which includes an isotope in a natural or unenriched state or an isotope which is enriched to a predetermined amount. The label is subjected to gamma radiation and the radiation is measured with the source of radiation being stationary and then with the source of radiation being vibrated. The measurements are then compared in order to determine the authenticity of the article.
2. Description of the Prior Art
As a result of technology advances in copying techniques and reproduction techniques, many articles are becoming very vulnerable to being counterfeited. This problem is becoming particularly acute in items such as credit cards, video tapes, cassette tapes, designer fashion accessories and clothing. In addition, an even more serious problem is occurring with regard to the counterfeiting of currency and other financial paper. A related problem is the unauthorized use of a financial item, such as a credit card, registered security or identity document.
Many techniques have been developed for labelling articles to prevent counterfeiting or fraudulent use. Techniques such as holograms on credit cards and magnetic coding on various articles have been in use for some time. These prior art techniques have been less than fully effective either because the counterfeiters have found ways to duplicate the label, or the apparatus for detecting the label and verifying its authenticity, has been too expensive to be utilized in the quantities necessary for preventing counterfeiting.